No doubt, the political A-listers gathering for the 18th annual summit have much to celebrate, starting with the spectacular views from the location near South Lake Tahoe. They also have their work cut out for them.

“We have our challenges, environmentally,” Amy Berry, CEO of the Tahoe Fund, said in an interview. “There’s a lot more to be done.”

Little time, for instance, remains for the current Congress to finish Lake Tahoe restoration bills introduced in both the House of Representatives and the Senate. The Lake Tahoe Restoration Act would authorize $415 million over 10 years for forest fuels management, watershed restoration, storm-water management and other projects. It would continue an earlier law passed in 2000 but that expired in 2010.

The House version introduced last October has not yet had a hearing.

Underscoring the political challenge, the House bill is not co-sponsored by Republican Rep. Tom McClintock, whose district spans California’s share of the 191-square-mile lake. In the Senate, where members of the minority party can easily erect roadblocks, four Republicans voted against the Senate’s version in committee in June.

“It’s a little frustrating,” Berry said of the legislative inaction, “but we know it’s a big bill.”

Brian Baluta, spokesman for the House bill’s author, Rep. Mark Amodei, R-Nev., said, “We hope to get a hearing by the end of this Congress.”

“I have supported the Tahoe Restoration Act in the past,” McClintock noted in an email Friday. “Right now I think we need to focus on those provisions that deal with fuels reduction, forest management and invasive species; these are the most critical threats to Tahoe and the surrounding region.”

McClintock and Amodei are scheduled to attend the summit, along with two governors, three senators and a host of others.

All told, about 450 people are expected at the summit, slated to last two hours at the lakeside Tallac Historic Site. California Democratic Sen. Dianne Feinstein, author of the Senate’s Lake Tahoe bill and owner along with her husband of a Tahoe City condominium, will host.

“Lake Tahoe is a special place, but it faces a number of threats including shrinking budgets and growing risks from climate change,” Feinstein said in a statement Friday, adding that the gathering “pumps vital energy into the federal, state and private partnership.”

Senate Majority Leader Harry Reid also will attend, on the heels of a $10,000-a-head fundraising weekend designed to benefit his Searchlight Lake Tahoe Victory Fund, according to an invitation first obtained by CQ Roll Call.

The high-level participation underscores the lake’s enduring political magnetism and ability to secure support. Since 1997, state, local and federal governments, along with the private sector, have spent more than $1.7 billion on the Lake Tahoe Basin.

But beneath their shared regard for the lake, which draws an estimated 3 million visitors annually, participating lawmakers differ on key points.

The summit, for instance, carries the theme of “confronting the effects of climate change on Lake Tahoe.” University of California, Davis, researchers note in an annual study released Aug. 14 that the lake’s average surface water temperature in 2012 was the highest ever recorded.

“With regard to climate change, we have really only scratched the surface,” Geoff Schladow, director of the Tahoe Environmental Research Center, said in a statement. “We have little understanding how extreme events will play out and impact the Tahoe Basin and the Sierra.”

McClintock attributes climate changes to normal fluctuations more than to manmade causes, calling the science unsettled and denouncing what he’s called “the war against carbon.” By contrast, California Gov. Jerry Brown, the summit’s keynote speaker, has called for “heroic efforts” to combat climate change.

The courtroom challenges have a different cast.

Last year, the Sierra Club and Friends of the West Shore sued the bi-state Tahoe Regional Planning Agency over the latest regional plan, which the environmental groups say increases the potential for new development.

In April, U.S. District Judge John A. Mendez in Sacramento dismissed the Sierra Club lawsuit, concluding the Tahoe planning agency acted properly. The fight is not over yet, though. In August, the environmentalists appealed to the 9th U.S. Circuit Court of Appeals.

“While the appeal makes its way through the legal process, we will continue to put the substantial environmental benefits of the plan into place,” the agency’s executive director, Joanne Marchetta, said in a statement.